In 9 euthyroid obese volunteers, 4 weeks of total caloric deprivation resulted in striking decreases in both total and free triiodothyronine (T3) concentrations in serum together with a slight increase in free thyroxine (T4) concentration. These changes were not associated with alterations in the basal serum TSH concentration or in the TSH or T3 responses to exogenous TRH. It is suggested that the decrease in serum T3 concentration that occurs during starvation results from decreased peripheral conversion of T4 to T3 and may explain, at least partially, the decreased serum T3 seen in clinical states associated with inanition.

No abstract